Ruby » Ruby master

thread.c: always deliver signal immediately

• thread.c (ruby_kill): always deliver signal immediately, without
  check for main thread. no longer called in other context.
  [ruby-dev:48203] [Bug #9820]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45912 b2dd03c8-39d4-4d8f-98ff-823fe69b080e